Embodiments relate to a semiconductor device including a vertical channel, and more particularly to a vertical-channel semiconductor device in which some parts of a lower portion of a buried gate are replaced with an insulation film so as to prevent a bit-line junction leakage.
Generally, a semiconductor is a material that falls within an intermediate region between a conductor and a nonconductor in terms of electrical conductivity. Although a semiconductor is similar to a nonconductor in a pure state, electrical conductivity of the semiconductor material can be increased by impurity implantation or other manipulation. The semiconductor is used to form a semiconductor device such as a transistor through impurity implantation and conductor connection. A device including a semiconductor element is referred to as a semiconductor device. A representative example of the semiconductor device is a semiconductor memory device.
A semiconductor memory device may include a plurality of transistors. The transistor may have three regions, i.e., a gate, a source, and a drain. Electric charges are moved between the source and the drain according to a control signal (the magnitude of a voltage) input to the gate of the transistor. The charges between the source and the drain move through a channel region in accordance with the properties and operation of the semiconductor device.
Generally, a method for manufacturing the transistor includes forming a gate over a semiconductor substrate, and forming a source and drain by doping impurities over the semiconductor substrate located at both sides of the gate. A region between the source and the drain may be located below a gate, and is used as a channel region of the transistor. A transistor including a horizontal channel region occupies a relatively large area, so that it may be difficult to form a highly-integrated semiconductor device.
In order to address the above-mentioned issues, there is proposed a vertical-channel semiconductor device in which an active region is formed as a pillar shape, and a source and drain region is located above or below the pillar, so that a vertical-shaped channel region is formed.
However, the higher the degree of integration of the semiconductor device, the shorter a physical distance between gate electrodes or bit lines, such that a bridge may occur between the gate electrodes or the bit lines, or parasitic capacitance between the gate electrodes or the bit lines increases. As a result, there is a need for a new structure capable of being highly integrated while also being easily fabricated.